Multiple abiotic and biotic drivers of long-term wood decomposition within and among species in the semi-arid inland dunes: A dual role for stem diameter

Enkhmaa Erdenebileg, Congwen Wang, Xuehua Ye, Qingguo Cui, Juan Du, Zhenying Huang*, Guofang Liu, Johannes H.C. Cornelissen

*Corresponding author for this work

    Research output: Contribution to JournalArticleAcademicpeer-review

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    Abstract

    Litter decomposition in sunny, semi-arid and arid ecosystems is controlled by both biotic factors including litter traits and abiotic factors including UV light, but for wood decomposition it still remains uncertain which of these environmental factors are the predominant controls among different woody species. In these dry ecosystems, it is likely that the stem diameter and spatial position of the dead wood are of particular importance especially where wood can be buried versus exposed due to substrate displacement by wind. Here we focus on the fact that stem diameter can affect decomposition rates both via the relative surface exposure to sunlight or soil and via higher resource quality of narrower stems to decomposers. In a field manipulation experiment, we investigated the relative importance of litter position (sand burial vs. surface vs. suspended above the surface), UV radiation (block versus pass) and stem diameter class (<2, 2–4, 4–8, 8–13 and 13–20 mm) on the mass loss of woody litters of four shrub species in an inland dune ecosystem in northern China. We found that after 34 months of in situ incubation, the mass loss of buried woody litters was three times faster than those of suspended and surface woody litters (53.5 ± 2.7%, 17.0 ± 1.0% and 14.4 ± 1.2%, respectively). In surface and suspended positions, litter decomposition rates were almost equally low and most mass loss was during the first 2 years, when bark was still attached and UV radiation had no significant effect on woody litter mass loss. These findings suggest that sand burial is the main environmental driver of wood decomposition via its control on microbial activity. Moreover, wood N and diameter class were the predominant factors driving woody litter decomposition. A key finding was that wider stems had slower litter decomposition rates not only directly (presumably via greater relative surface exposure) but also indirectly via their higher wood dry matter content or lower wood N; these effects were modulated by litter position. Our findings highlight a dual role of stem diameter on wood decomposition, that is, via relative surface exposure and via wood traits. The accuracy and confidence of global carbon cycling models would be improved by incorporating the different effects of stem diameter on woody litter decomposition and below-ground wood decomposition processes in drylands.

    Original languageEnglish
    Pages (from-to)1472-1484
    Number of pages13
    JournalFunctional Ecology
    Volume34
    Issue number7
    Early online date20 Mar 2020
    DOIs
    Publication statusPublished - Jul 2020

    Funding

    We thank Jianlin Zhang, Hongmei Mao and Zhaoren Wang for their assistance in the setup of the litter incubation experiment. We thank the National Field Research Station for Ordos Grassland Ecosystems in Inner Mongolia of China and the Ordos Sandland Ecological Research Station, CAS for providing the research site and relevant climate data. This work has been supported by grants of the National Key Research and Development Program of China (2016YFC0500501, 2018YFE0182800) and the National Science Foundation of China (NSFC, 31470712) to G.L., The CAS President's International Fellowship Initiative (PIFI, 2018VCA0014) for J.H.C.C. and the CAS-TWAS President's Fellowship for International PhD Students for E.E. We also declare that all coauthors have no conflict of interest.

    FundersFunder number
    National Field Research Station for Ordos Grassland Ecosystems in Inner Mongolia of China
    Ordos Sandland Ecological Research Station
    National Natural Science Foundation of China2018VCA0014, 31470712
    Chinese Academy of Sciences
    National Key Research and Development Program of China2018YFE0182800, 2016YFC0500501

      Keywords

      • dryland
      • functional traits
      • litter position
      • sand burial
      • shrub encroachment
      • stem diameter
      • wood litter decomposition

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